• Journal of the Society of Naval Architects of Korea
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• v.49 no.4
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• pp.281-286
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• 2012

Single frame structures with notches were fractured by applying drop impact loadings at room temperature and low temperature. Johnson-Cook shear failure model has been employed to simulate the fractured single frame structures. Through several numerical analyses, material constants for Johnson-Cook shear failure model have been found producing the cracks resulted from experiments. Fracture strain-stress triaxiality curves at both room temperature and low temperature are presented based on the extracted material constants. It is expected that the fracture strain-stress triaxiality curves can offer objective fracture criteria for the assessment of structural fractures of polar class vessel structures fabricated from DH36 steels. The fracture experiments of single frame structures revealed that the structure on low temperature condition fractures at much lower strain than that on room temperature condition despite the same stress states at both temperatures. In conclusion, the material properties on low temperature condition are essential to estimate the fracture characteristics of steel structures operated in the Northern Sea Route.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.263-266
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• 2002

Rises of temperature and resistance are observed in HTS tapes under over current condition. In this paper, we measured HTS tapes properties under low-over current condition with a little temperature rise as well as high-over current condition with a large temperature rise. According to the results of measurement, rises of temperature and resistance strongly depend on insulation level and duration of over current condition.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.273-276
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• 2004

Recently. cold weather constructions were popularized because of the importance of construction term. The special method about mix design and curing of concrete was being planned to conduct cold weather constructions, but these method were not considered in a low temperature time. A Strength revelation of concrete is delayed in a curing condition of low temperature. If a construction was loaded in this case, cracks or remaining deformations are generated in a construction. So, a strength revelation characteristic in early age was investigated to secure early strength of concrete in curing condition of a low temperature. In this study, the method about concrete mix design was presented to secure construction safety in a low temperature time.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.12
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• pp.1-8
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• 2012

The performance and lighting characteristics of the LED depend on cooling condition because the power LED generates lots of heat. In this paper, the effect of the generated heat from power LED module on lighting characteristics and performance is measured and evaluated. For experiments, the transient temperature of a power LED module with cooling condition is measured. In addition, the temperature and lighting characteristics of the LED module are measured during the steady state. As a result, the cooling condition is less effective on the lighting characteristics of the LED module at rated current but the cooling condition extremely affects those of the LED module over the rated current. Because high temperature of the power LED module causes the low phosphor conversion, luminance efficiency becomes low and color temperature becomes high. When power LED module are driven over the rated condition, higher temperature is directly related to lighting characteristics and performance of the LED module rather than higher current.

• Journal of Korean Society on Water Environment
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• v.22 no.2
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• pp.258-263
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• 2006

ANAMMOX (Anaerobic ammonium oxidation) reactor, which was cultivated ANAMMOX bacteria in mesophilic condition ($35^{\circ}C$), was operated to investigate the effects of temperature. In $20{\sim}30^{\circ}C$ of operation condition, which was assumed as field-temperature, total N removal and $NH_4-N$ removal rate were declined from about 2.50 and $1.27kg\;N/{m^3}_{reactor}-day$ (0.06 and 0.03 kg N/kgVSS/day) to 1.62 and $0.41kg\;N/{m^3}_{reactor}-day$ (0.04 and 0.01 kg N/kgVSS/day), In this range of temperature, ANAMMOX had very low activities but acid fermentation bacteria and denitrifiers, which were competitors of substrates, had high activities relatively. Though operation temperature was higher than inhibition condition for two months, ANAMMOX activities could not been recovered once they were inhibited by low temperature. This fact was resulted from very slow doubling time of ANAMMOX bacteria. This study shows that maintenance device of optimal temperature is necessary required in field application of ANAMMOX.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.349-354
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• 2002

A size of low-voltage conductor cables is determined by the voltage drop of a system, the cable impedance and the cable ampacity based on temperature correction factor in accordance with the condition of cable installation. Therefore, the proper temperature correction factor according to the condition of cable installation should be applied to determining the cable ampacity and also the skin effect and proximity effect, along with the kind and size of conductor and the condition of cable installation, should be properly considered to analyze the proper value of resistance and the reactance of the conductors. This paper addresses the systematic design flow for determining the size of low voltage level conductor cables in calculating the temperature character where error should be minimized in comparison with the general formula and which can be applied in design work for determining the size of conductor cables.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.23 no.1
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• pp.1-4
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• 1978

The change of soluble protein components in leaf discoloration of rice plant was investigated in the Growth Cabinet with various temperature conditions. The ratio between high molecular soluble protein and low molecular soluble protein was high under high temperature condition, while low under low temperature condition, and also lower in Indica type varieties than Japonica type variety.

• Journal of Aerospace System Engineering
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• v.13 no.4
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• pp.18-25
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• 2019

Studies on the fabrication of UAV by using 3D printer have been actively carried out. However, research on structural load characteristics in low temperature environment is insufficient. In this study, a composite sandwich structure with ordinary orbs structure was proposed, and the load characteristics for temperature condition changes were analyzed. The ordinary orbs and honeycomb structures were fabricated by using a FDM type 3D printer. The bending load test was carried out at room temperature and low temperature condition. The low temperature condition was classified into four cases. Bending load tests were performed in a low temperature chamber to maintain the required temperature conditions. As a result of the test, it was confirmed that the proposed ordinary orbs structure had better load characteristics at low temperatures than the existing honeycomb structure.

• Journal of the Korean Society of Tobacco Science
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• v.7 no.2
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• pp.129-139
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• 1985

cent was carried out to study on the effect of temperature and humidity to chemical tobacco leaves during the yellowing stage. The results were follows : In the condition of high humidity and low temperature, yellowing time was delayed ; leaf color appeared lack clearness. In the higher temperature and the lower humidity during the yellowing stage : total sugar, reducing sugar and malic acid content were increased. Decomposition of nitrogenous components elevated in $38^{\circ}C$, 85%RH. Changes of total nitrogen content correlated with total curing time. Adecrease of linolenic acid with a corresponding increase of chlorogenic acid proceeded in the condition of low temperature and high humidity. In a view of tobacco quality by chemical components, the low temperature and high humidity during the yellowing stage decreased quality of tobacco leaves. It is considered to control of the proper condition of temperature and humidity during the yellowing.

• Journal of the Korean Society of Combustion
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• v.18 no.2
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• pp.32-41
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• 2013

This study presents both experimental and numerical investigation of ignition delay time of n-heptane and n-butanol binary fuel. The $O_2$ concentration in the mixture was set to 9-10% to make high exhaust gas recirculation( EGR) rate condition which leads low NOx and soot emission. Experiments were performed using a rapid compression machine(RCM) at compressed pressure 20bar, several compressed temperature and three equivalence ratios(0.4, 1.0, 1.5). In addition, a numerical study on the ignition delay time was performed using CHEMKIN codes to validate experimental results and predict chemical species in the combustion process. The results showed that the ignition delay time increased with increasing the n-butanol fraction due to a decrease of oxidation of n-heptane at the low temperature. Moreover, all of the binary fuel mixtures showed the combustion characteristics of n-heptane such as cool flame mode at low temperature and negative-temperature-coefficient(NTC) behavior. Due to the effect of high EGR rate condition, the operating region is reduced at lean condition and the ignition delay time sharply increased compared with no EGR condition.